BETTER AND SAFER CROWN INSULATION

      Lubisol Engineering Co. has 20 years experience in the field of thermal insulation and hermetic sealing of glass furnace silica crowns. As a result of our studies we implemented the latest trends among the leading glass companies that the standard crown insulation can and should be further improved. A large number of glass furnace crowns of small or medium size glass producers are still insulated with only 3-4 layers of light silica brick. This type of insulation has been used without significant change during the last 50 years, and it reflects the conservative attitude prevailing in some areas of the glass industry and the fear from “over-insulation”. According to the latest world trends the crown insulation should be made much more efficient for saving of energy and fuel and this may also help for reducing the rate of condensation corrosion and rat-hole formation.

      Lubisol Engineering Co. offers special refractory materials, application technology and know-how for improving the furnace crown design. LUBISOL aims to encourage the glass producers to apply crown thermal insulations with maximum efficiency in order to reduce energy losses and fuel consumption. In the same time the company is offering a new original solution for hermetic sealing. It helps for increasing the furnace crown life and improving the safety factors against condensation corrosion and rat holing.

REDUCING HEAT LOSS

      Heat losses from a silica crown with 3-4 layers of light silica brick insulation are about 2000 W/m2. A further increase of the thickness of this type of insulation gives no further advantage because of the rising conductivity of the material at higher temperatures. A better solution is to combine light silica with other more efficient insulating materials.

      LUBISOL’s standard insulation package for a new crown incorporates a layer of 64 mm light silica brick, followed by 1 layer of  114 mm Lubisol #2-SL and 30 mm Lubisol #3 Covering Cement. This package is suitable for cold or hot application – before or after the heating-up. With this insulation the heat losses from the crown can be further reduced down to 1100 W/m2, bringing additional energy savings of   900 W/m2, and fuel savings of 1260 m3 natural gas for 1 m2 crown area per year. The cost of the saved fuel is 400 €/m2/year and for a mid size furnace with 100 m2 crown – about 40 000 €/year.

HERMETIC SEALING

      In cases when special protection against rat-holes is needed, the insulation starts with a layer of 30 mm Lubisol Si-Seal kit applied directly over the silica crown. This material develops a very strong adhesive bond and hermetic sealing ability with the silica bricks. This is recommended for all type of glass furnaces, especially for furnaces melting highly aggressive glasses and furnaces with oxy-fuel firing. This is strongly recommended to companies having rat-hole problems in previous campaigns.

LONG-TERM BENEFITS

      Observations over a long period of time on large number of furnaces indicated, that the upgraded crown insulation leads to big fuel savings and long service life of the crown without rat-holes.  Glass melting has been carried out at the same maximum furnace crown temperature and the only difference has been the reduced consumption of gas or oil.

       The main advantage of the Lubisol insulation package is the very low specific weight and high efficiency of the insulating material Lubisol #2-SL having a specific gravity of only 0.33 kg/dm3 and a thermal conductivity of 0.08 W/m.K. This contributes to reducing the thickness, the total amount and cost of the insulation materials needed.

       The cost of this Lubisol package based on efficiency is lower than the price of conventional crown insulation, so the company is able to offer very light and highly efficient crown insulation at a competitive low price with a return on investment in less than one year.

      The LUBISOL materials have been applied so far on more than 100 glass furnaces around the world. The LUBISOL package being light and highly efficient in a rather small thickness is very suitable for the insulation of all type glass furnaces, especially for the large span container and float glass furnace crowns.  

       By reducing the heat losses and fuel consumption in the glass industry, LUBISOL is participating with a contribution helping for environment protection against the climate change.

Contact: Prof. S. Lutskanov, e-mail: lubisol@ttm.bg  office@lubisol.com

              Fax: +359 2 9753 291   www.lubisol.com   www.lubisol.ttm.bg

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